Structured Cabling Channel Length (TIA-568)
Whether a twisted-pair horizontal channel is within the TIA-568 limits.
Example
You enter
- Permanent-link length (m) 85
- Total patch + equipment cords (m) 8
- Installed cable temperature (°C) 20
- Cable: 0.004 = UTP, 0.002 = screened (TIA Table G.2); other = custom linear de-rate per °C 0.004
You get
- Permanent link vs de-rated max 90
- Channel vs 100 m 93
Checked against published worked examples from: Telecommunications Industry Association (TIA), ANSI/TIA-568-C.2 Annex G, as posted to...
Details, formula, and sources
Scope100 m total = a 90 m permanent link plus up to 10 m of patch and equipment cords, with the permanent-link maximum de-rating above 20 deg C per TIA-568-C.2 Table G.2 (UTP 84.0 m at 40 deg C, 75.0 m at 60 deg C). An 85 m link with 8 m of cords at 20 deg C passes (93 m channel, link within the 90 m max); at 40 deg C the max link de-rates to 84.0 m (TIA-568-C.2 Table G.2) so the 85 m link fails and must be shortened. A design aid; the cable's published de-rating and the adopted TIA-568 edition govern.
Formula or tablemax_pl = TIA-568-C.2 Table G.2 (unscreened 90.0/89.0/87.0/85.5/84.0/81.7/79.5/77.2/75.0 m, screened 90.0/89.5/88.5/87.7/87.0/86.5/85.5/84.7/83.0 m at 20-60 deg C in 5 deg steps), interpolated; a custom rate uses 90 x (1 - max(temp - 20, 0) x rate); channel = permanent_link + cords; pl_ok = permanent_link <= max_pl; chan_ok = channel <= 100 m.
Source and editionANSI/TIA-568 (Balanced Twisted-Pair Telecommunications Cabling) 100 m channel model and the temperature de-rating of the permanent link, by name.
Free accessThe 100 m channel / 90 m permanent-link model and the temperature de-rating are published in ANSI/TIA-568; the arithmetic is public.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namespermanent_link_m, cords_m, temp_c, derate_per_c, max_pl_m, channel_m
- 100 m channel channel = permanent link + cords <= 100 m, with the permanent link <= 90 m at 20 deg CANSI/TIA-568
- Temperature de-rate max permanent link from Table G.2 (84.0 m UTP / 87.0 m screened at 40 deg C; 75.0 / 83.0 at 60); the 0.4%/deg C UTP figure is the insertion-loss rise behind the table, not a length cutANSI/TIA-568-C.2 Annex G
- Manufacturer governs the adopted TIA-568 edition and the cable's published de-rating governscope of this tile